Electric discharge lamp



y 936. E. OOSTERHUIS ET AL 2 039,978

ELECTRIC DISCHARGE .LAMP

Filed Sept. 3, 1931 [WE N, TURE' EZKKU "U05 TERHUZE Gus TA I Z EEHER THEIR. Ar Tara. NEY'.

Patented May 5, 1936 ELECTRIC DISCHARGE LAMP Ekko Oosterhuis and Gustav Zecher, Eindhoven, Netherlands, assignors to General Electric Company, a corporation of New York Application September 3, 1931, Serial No. 561,040 In the Netherlands September 11, 1930 3 Claims.

Our invention relates to electric discharge lamps and more particularly to such lamps used for the production of ultra-violet radiations.

It is sometimes desirable to add visible light 5 waves to the spectrum of the emitted light, which consists mostly of ultra-violet rays. Up to the present time, this has been accomplished by inserting a filament in series with the electrodes of the discharge tube. It has been shown that the life of such a filament is very short due, probably, to the fact that it is disintegrated by electric discharges. I

The object of our invention is to so dispose the lighting filament in the bulb as to render it free from the effects of the hereinbefore mentioned discharges. We accomplish this by placing the filament which is to emit visible light rays in a circuit separate from that of the discharge electrodes, that is, there is no physical connection between the two circuits. It seems that the filament is less subject to disintegration in this case and therefore has a longer life.

Other features and advantages of our invention will appear from the following description of species thereof.

In the drawing Fig. 1 shows a discharge device I comprising our invention; and Fig. 2 is a diagrammatic view of the wiring diagram.

Referring to Fig. 1, the discharge tube comprises a bulb l and stem tube II. A cathode I2 is mounted on inner lead wires l3, l4 sealed into a stem press l5 which also envelops outer lead wires I6. Two anodes l1, l8 consisting preferably of molybdenum plates, are supported by inner 35 lead wires [9, 20 which are sealed into the stem press l5 and connected to outer lead wires 2|, 22 respectively. A filament 23, consisting preferably of a tungsten coil, is supported by irmer lead wires 24, 25 which are also sealed into the stem press l5, and are connected to outer lead wires 26, 21 re spectively. The bulb I0 is filled with a rare gas, such as argon, at a pressure of approximately 1 mm., to which is added a small amount of mercury vapor. For this purpose a few drops of liquid mercury are placed in the bulb. By gas filling is meant not only a filling of one or more gases, but also of one or more vapors, or'a mixvided to supply current to the filament 23 at a potential of, for example, 7 volts.

In operation, an arc discharge takes place between the cathode l2 and anodes I1, l8. This discharge, taking place in a vapor of mercury, produces ultra-violet rays which pass through the wall of the bulb M which is made of a glass transmitting ultra-violet rays. The filament 23 becomes incandescent, so that the bulb may be used for purposes of illumination as well as a source of ultra-violet rays.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electric lamp comprising a pair of solid electric discharge electrodes, a filament connected in multiple and disposed between said electrodes and another filament adapted to be heated to incandescence to provide illumination and disposed out of line with said electrodes, said second-mentioned filament being connected to a source of electrical energy separate from that to which said electrodes are connected, there being no electrical connection between the circuit containing said filament and the circuit containing the electrodes.

2. An electric lamp comprising a sealed en-' velope capable of transmitting both visible radiation and short wave ultra-violet radiation and containing an ionizable medium and a pair of solid electrodes for passage of an arc therebetween including means for initiating an are discharge between said electrodes, and a filament in said bulb adapted to be heatedto incandescence to provide illumination and disposed out of the line between said electrodes, said filament being connected to a source of electrical energy separate from that which said electrodes are connected, there being no electrical connection betweeen the circuit containing said filament and the circuit containing the electrodes.

3. An electric lamp comprising a sealed envelope capable of transmitting both visible radiation and short wave ultra-violet radiation and containing an ionizable medium and a pair of solid electrodes for passageoi' an arc therebetween, a filament connected in multiple and disposed between said electrodes, and another filament in said bulb adapted to be heated to incandescence to provide illumination and disposed out of the line between said electrodes, said secondmentioned filament being connected to a source of electrical energy separate from that to which said electrodes are connected, there being no electrical connection between the circuit containing said filament and the circuit containing the electrodes.

GUSTAV ZECHER. 

